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HF Amplifier


#1

A limited mobility friend of mine has a FT-817 and has asked me about a small linear amplifier to take it up to about 20 watts for ‘low level’ portable operations. He is power restricted because he uses an elecraft T1 auto tuner which is max rated at 20 watts. Does anyone use a small amp on HF with this rig and if what?

many thanks
73 Glyn


#2

In reply to GM4CFS:
Glyn - Richard G3CWI is your best bet with the question.

73

Jack (;>)


#3

In reply to GM4CFS:
The Tokyo HL-50B is often used with the 817. It gives 50W out for 5W in; obviously you can reduce the drive to get 20W. I used one as my main home rig for some time.

My only comment is that it is a bit touchy about the load. Present it with a bad match and it just trips out. So to use it with an autotuner, you have to be able to tune up barefoot first, then switch on the amp.

I bought mine second hand; no idea whether it is still available new.


#4

In reply to GM4CFS:

Why not just use an 857 + linked dipole & turn power down to 20w if you want. No tuner needed so extra weight of rig offset by no weight of tuner. Just a thought.


#5

In reply to DH8DX:

What a difference your extra power gives Dan! No problems copying you this week.

Your signals were 559-579 from all summits, whereas stations from EU using 5w to a standard antenna are either just on the noise level or totally inaudible to me. Many Thanks.

73
Roy G4SSH


#6

In reply to 2E0HJD:

Nice move Dan with the QRO, your sigs are superb now and easy to copy even in qrm.

Today on NW-064 I took my 857D, linked dipole and 7ah slab and made 40 contacts to UK 2m-ssb/fm and 60m-ssb then 40m cw to EU running between 25-70 watts, it’s definately the way to go.

I still think that the 817 is a superb all rounder under the right conditions but I can’t argue with the results from the 857.

73 Mike GW0DSP


#7

In reply to 2E0HJD:

Having now done 2 activations with the master (INKy) and seen how the big boys do it, how can I argue Mick?

The results speak for themselves and are the proof of the pudding…

The Cloud with 817 and I managed just 17 contacts, today with the 857 = 40 contacts, end of story.

73 Mike


#8

My next stage is to buy a pack animal to carry a couple of 120Ah batteries and a 400w linear to within a few feet from the summit, but I can’t decide between a Yak and a Llama. I won’t buy a donkey is case I get comments about the size of my ass ;oD

Seriously I too have been thinking of going down the 857 route as it is much lighter and less current hungry than the 706 I used in Scotland, but what are the alternatives? I had concidered the SGC2020 (20w) but SGC have ceased production to concentrate on their autotuners. I am also thinking that SLA batteries are too heavy and I would seriously think of spending whatever it costs to get something lighter> Anyone know how big these Lithium/Polymer cells go?

73 Steve GW7AAV


#9

In reply to 2E0HJD:

I personaly have a s9 noise
level at the home qth on the lower bands dropping to about s7 around
20m. and it is getting worse with passing months. i blame it on
pc`s,phone chargers, games consoles,digital tv boxes etc etc it seems
there are no checks on any of he imported junk from Hong Kong into the
uk at all these days.
QRO is the way to go
Mick

Ps i can only work what i hear !!

Hi Mick, have you tried identifying the local noise sources ?.

I have succesfully done so at my home QTH, reducing 20m noise from S7 to S0.

I did this by making small magnetic loops out of house wire for each band and tracking down the noise sources. These were then addressed by fitting split ferrite rings (TDK) to power leads and high pass filters to tv aerials etc.

The worst offenders were low voltage lighting in the bathrooms and the tv.

I also fitted ferrite and high pass filters to my neighbours tv after she complained about tvi, which solved her problems and mine.

You can also use antennas with lower local noise pickup. e.g. Magnetic loops and/or shielded loops for the low bands. Half wave loops/square dipoles (cobbweb) have lower noise pickup than straight dipoles. Hex beams / moxon rectangles have lower local noise pickup than straight yagis (in my opinion).
Verticals are awful for noise pickup, but you can often make a dramatic difference by moving them just a few meters further away from a noise source.

As you say if you cant hear them you cant work them !.

Best Regards,
Nigel. G6SFP.


#10

In reply to 2E0HJD:

Mick and others - This packhorse qro is fine if you only have to move your station a few hundred metres but try some of the GM summits with a unbelievably heavy pack: 1 1/4hrs on a bike, 3 1/2hrs to the summit with 800m of ascent, 3hrs down and another 1hr on a bike - and that is my local 10 pointer! I make every effort to make my pack as light as possible especially as it is essential to carry water, foul weather gear and spare provisions for safety’s sake. The only way a rig any heavier than an 817 would be carried (and Li-Ion batteries) would be with help; and a large SLAB - never!

73

Barry GM4TOE